Trailblazers in plasma turbulence computer simulations win 2024 James Clerk Maxwell Prize

(Press-News.org) A pair of physicists with long ties to PPPL are being honored for their foundational work on turbulence in plasma. Understanding why instabilities occur and how to limit them is critical to perfecting fusion as a stable energy source for the electrical grid. 

Greg Hammett, a PPPL theoretical and computational principal research physicist, and Bill Dorland, former associate laboratory director for computational sciences and current Lab adviser, have won the 2024 James Clerk Maxwell Prize for Plasma Physics. The American Physical Society (APS) awards the $10,000 prize annually to recognize outstanding contributions to the field of plasma physics. 

“Greg Hammett and Bill Dorland are world leaders in the development of theories and computer simulations regarding turbulence in confined plasmas. Their work has revolutionized high-power computer calculations for transport regarding plasma turbulence in both astrophysical plasma and in the magnetically confined plasmas we experiment with for fusion,” said Steve Cowley, PPPL’s Laboratory director and a longtime collaborator with Hammett and Dorland. “I am so pleased to see their hard work recognized by the APS.”

Their recognition follows in the footsteps of other PPPL legends, adding yet another chapter to the Lab’s storied legacy in plasma physics. The Maxwell Prize was first granted in 1975 to the Lab’s founder, Lyman Spitzer. Several other PPPL researchers have also won the award, including Amitava Bhattacharjee, Nat Fisch, Russell Kulsrud, and Masaaki Yamada.

“It’s an honor to get this award, and I hope it’s also seen as recognition of the excellent work by many people who have helped our field,” said Hammett. “When I started, most scientists in the field thought of turbulence in plasmas as an intractably hard problem. They’d say, ‘Don't even bother trying to understand it.’” However, with advances in the tools used to measure plasma parameters and computing power — and essential insights from Hammett and Dorland — came useful computer simulations that have grown better and better at simulating real-world behavior. Sophisticated computer simulations developed by them and others in the fusion community are harnessing the power of modern supercomputers to understand existing fusion experiments and search for ways to improve future fusion power plants. 

Decades of work, dozens of papers

Hammett and Dorland’s decades of work — including more than 45 papers written together — goes all the way back to the early fluid approximations Dorland explored in his doctoral thesis when Hammett was his adviser. “Greg was my Ph.D. adviser, and I was his very first student. That’s why we’re tied together at the waist,” said Dorland.

Plasma turbulence can limit the maximum temperature in a fusion device and, thus, can limit how much fusion power it makes. Using a combination of analytical techniques and numerical methods to calculate rapid fluctuations in turbulence, the pair enabled research that would not have been possible without their work. 

Turbulence is also a common phenomenon in nature, seen in the air moving around airplanes, fluids flowing through pipes and the eddies of water that form around ships, so it’s little surprise that Hammett and Dorland’s work has also inspired work in the astrophysics and solar wind research communities. 

“We were very lucky to have such a brilliant pair ask the right set of questions from the start. It made it so much easier for those of us that came after. I simply cannot imagine where we would be without them. Probably 20 years behind!” said Felix Parra Diaz, head of PPPL’s Theory Department and nominator of Dorland and Hammett. “They were also extremely generous with the community, sharing their computational tools widely and helping with the analysis of experiments.”

Hammett: A child of the space race

Hammett says his interest in physics began in his youth when he watched news about the Apollo moon missions. Hammett’s father, a U.S. Air Force fighter pilot and hot-rodder, was always interested in “technical things” and fostered his love of the field. “Then we were in the middle of the first energy crisis, and fusion research seemed like a good way to combine physics interests into something that might be practical and useful,” he said.

Hammett came to PPPL in 1980 as a graduate student at Princeton University after earning a bachelor’s degree in physics from Harvard University. He has taught graduate courses for nearly 30 years, has been a lecturer with the rank of professor in the Princeton Program in Plasma Physics since 2001 and is an associated faculty member with the Program in Applied & Computational Mathematics at Princeton. An APS fellow, he has co-authored more than 225 papers, many highly cited.

Dorland: Filled with emotion

Despite the duo’s prolific authorship, Dorland said he was completely surprised when he was told they had won the Maxwell Prize. "I was filled with emotion and overwhelmed,” said Dorland. “I've just been walking on air since.”

Dorland was the founding head of the Computational Sciences Department at PPPL and continues to support its growing initiatives as a special adviser to Cowley. Dorland is a professor of physics at the University of Maryland and a member of Maryland’s Institute for Research in Electronics and Applied Physics. He is also a visiting professor of physics at the University of Oxford. He received a bachelor’s degree in physics from the University of Texas at Austin with special and highest honors and a doctoral degree in astrophysical sciences from Princeton University in 1993, as well as a master’s degree in public affairs from the Princeton School of Public and International Affairs, where he focused on science policy. Dorland won the 2009 Ernest Orlando Lawrence Award of the U.S. Department of Energy for his work on the theory and simulations of turbulence in fusion reactors, and he is a fellow of the APS. 

Dorland has been highly committed to inspiring and mentoring students in plasma physics, particularly undergraduate students. He is a University of Maryland Marquee Courses in Science and Technology faculty member, part of the Merrill Presidential Scholars Program faculty and a University of Maryland Distinguished Scholar-Teacher. He served as the founding executive director of the university’s Honors College for seven years. 

“Particularly important colleagues in our work have been Steve Cowley, Mike Kotschenreuther at the University of Texas at Austin, Ron Waltz and Jeff Candy at General Atomics, Alex Schekochihin at the University of Oxford, and Mike Beer (now a professor of biomedical engineering, genetic medicine and oncology at Johns Hopkins University) who was a Princeton graduate student in plasma physics and then a scientist at PPPL,” Hammett said. 

Both also said they were fortunate to have families who encouraged their scientific pursuits. Hammett expressed his gratitude to his wife, Kate, for her continued encouragement and helping balance his life. Dorland also extended heartfelt thanks to his wife, Sarah, and their daughter, Kendall, for their unwavering support. 

Hammett and Dorland will accept their award “for pioneering work in kinetic plasma turbulence that revolutionizes turbulent transport calculations for magnetic confinement devices and inspires research in astrophysical plasma turbulence” this October at the annual meeting of the APS’ Division of Plasma Physics in Atlanta.

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